# Symphony Stdlib

This is a standard library for symphony.
It is both intended as a practical toolkit to develop more complex software as well as a teaching resource.

If you just want to use the standard library [[stdlib.asm]] is your main header, include it after your code.
You'll also need to include globals.asm in the first line of your main assembly file.

If you are using it as a learning resource have a look at the [teaching folder](teaching).

If you are intersted in contributing have a look at [[CONTRIBUTING.md]]

---

## ABI

### Calling Convention
| class | registers |
| ----- | --------- |
| n.a. | zr |
| preserved | sp, r8 - r12 |
| scratch | flags, r1 - r7 |
| arguments | r1 - r5, r6 = stack args, r7 = stack res |
| result | r1 = low word, r2 = high word |
| return address | r13 |

### Stack
grows downwards from top of memory
arguments are passed in reverse order with the stack so:
lowest address = 1st stack arg
highest address = last stack arg

### Types

#### String
Strings are stored in memory as null terminated sequences of bytes encoding ascii characters.
They should be passed by reference.

#### Array
Arrays are stored in memory with a reference to them being the tuple (pointer, length) stored in a register pair.
Array elements may only have a size of 8/16/32 bits